Of all the Japanese arts, rakugo traditional comedy is one of the most impenetrable for foreigners. The premise is simple: kimono-clad practitioners tell old funny stories on stage that culminate in a punch line called the ochi, with only a fan and handkerchief as props.

In the hands of an expert hanashika (storyteller) raconteur, these can become anything from a sweet potato to a samurai sword, conjuring Edo times (1600-1868) from which most narratives descend. Changes in gesture and voice to depict characters are important, but language is crucial. Unlike plays at the Kabukiza, there is no English guidance for the stories, and if your Japanese isn’t up to grasping Edo puns, you won’t be in on the joke.

It’s no surprise that few non-Japanese patronize Tokyo’s four yose (rakugo theaters); most Japanese find the art mystifying too. That is a shame because rakugo is unique; it’s an interactive aural tradition fully alive to its audience and contemporary reality — not subsidized theater frozen in time. Happily, when I stumbled upon the Suehirotei yose in Shinjuku recently, its friendly manager offered me a copy of a book that helps explain the genre.

Lorie Brau’s “Rakugo” is a significant piece of scholarship that examines the value of rakugo as a living heritage. It’s billed as an introduction and contains a detailed history and several translated stories, but its core is ethnography based on participant observation and anecdotes. Brau was apprenticed to a hanashika called Kokontei Engiku for a few months in the early 1990s and most of her research and sources date to that period — the book’s shortcoming is that it took some 15 years to see the light of day. There is some discussion of how new media, such as cell-phone downloads, have affected rakugo’s public profile in the past decade, but Brau is more concerned with how rakugo is structured, passed on and consumed.

She reveals a group of comedians that could not be more different from the irreverent stand-up comics of America. Hanashika learn their craft from mentors called shishou, form clannish artistic families and larger organizations, and observe rigid internal hierarchies and protocols to ingratiate themselves with superiors and fans. Apprentices, known as zenza, spend their days dressing their masters, doing housework, and beating the yose drums. Backstage, a pecking order worthy of any barnyard is enforced: the highest-ranked hanashika get special dressing room seats, their footwear gets top shelf on the shoe rack, and no one speaks out of turn. “In their formulaic interactions,” Brau writes, “hanashika prize brevity, as I discovered when I tried to add a few pleasantries as I was serving tea as a zenza. One of my superiors told me to stick to the script.”

Of course, much of the above is standard in Japanese society. Rakugo’s appeal is predicated on individual artists, however, and storytellers are also innovators. They can put a new shine on classics by editing and salting them with modern puns, impersonations, and impromptu gags. Character portrayal is key to novelty. “The fundamental virtue of rakugo,” Brau notes, “is in the way in which the performer embodies the character.” Rakugo has also been enlivened by foreigners like Diane Orrett who have taken it up.

Vying for attention in an ever more congested entertainment space, rakugo’s old-world clowns can still fill halls and kill audiences. These artists embody the past through stories handed down through generations, and yet their jokes never get stale. This study is detailed and at times fascinating. The author’s intimate understanding of this art forms a basis for making a convincing case that humor is a form of cultural heritage.